I'm not the top indoor grower I must admit, but since no one else commented I guess I can. I have an area 4x8 feet with 2 400W MH bulbs. I grow various South African winter growing plants under these and some are within 2 inches of the glass plates protecting the light bulbs. These are on a 12 hr cycle. I keep a small oscillating fan going primarily to keep the air moving rather than heat dissipation, but they will got hot right under the bulb.....not a problem at all for my plants, but I'm using 400W not 1000W. I've been doing this for 5-6 years now and my plans, which like the brightest light possible, stay reasonably compact with my set-up. You will want the light closer than what you mention though. Best of luck with your plants :o) Dan

Thanks for the reply Dan! I think I'll give the MH a try, do some experimenting and over time adjust things as needed. I might even go with a 400W light for now and get a switchable MH/HPS 400W addition later.

In your experience, have you had success with MH indoors for full vegetative growth?

In my experience, adding a 1000 watt incandescent bulb to a 1000 watt Sylvania Metal Arc (regular MH) bulb more than doubled the growth rate of plants. My conclusion was that extra far red light dramatically improves the performance of regular MH.

Therefore, I recommend that you use a special MH with extra far red light, e.g., Philips Ceramic Metal Halide 4K (for HPS ballast) or Eye Hortilux Blue. If you use a regular MH, you should supplement it with a far red light source. As a supplemental far red source, Philips White Son® is about 3X as efficient as incandescent. I suspect that a 400 watt regular MH in combination with a 100 watt Philips White Son® would be a good combination.

As a side note... And just an FYI...

I use my basement as an indoor greenhouse. I set it up some years ago but life got in the way and I haven't used it for awhile. Anyway, I set it up with a 1000 watt Hortilux HPS and I found the stems on my developing plants weren't as sturdy as I would like them to be. I researched it and two options were presented 1) use a fan to simulate outdoor conditions, and 2) use a track to simulate the movement of the sun. I had been using a fan all along and had weak stems. Option 2 worked. Keeping the light moving seemed to make a big difference. Within a very short time the stems were very sturdy -- most noticeably on the tomato plants, but I also had a variety of flowers for the garden -- mostly perennials. When I set the plants out in the spring they were ready to face the environmental challenges. It was a "learn as you go" situation :)

Keeping the light moving seemed to make a big difference.

Are you sure that isn't because the light isn't diffuse enough? Do you have white painted walls, ceiling and maybe even floors around the plants?

Could be, but it seems logical that the plants would lean toward the light which would strengthen their stems. I've always used a light meter so I am aware of how much light the plants get.

Do you have white painted walls, ceiling and maybe even floors around the plants?

Yes, the walls are white. I'll try to take a picture and put it on here, but at the momeny all I have is my phone to do digital pictures with.

Sorry, typo -- too quick to click and there doesn't seem to be a way to correct it.